Soil carbon pool is an important carbon pool of terrestrial ecosystems. The mountainous areas account for about 25% of the world's surface area. Study on variations of the soil organic carbon storage in mountainous areas and their influencing factors is of great significance for enriching the soil carbon cycle theory of terrestrial ecosystems. On the northern slope of the Taibai Mountain in the Qinling, the sampling sites were set at every 50 meters above sea level to explore characteristics of the soil organic carbon storage along an altitude gradient. The results showed that altitude gradient had a significant impact on the soil organic carbon density (SOCD). The SOCD of different soil thicknesses increased by 10%-88% with the increasing altitude gradient. The climate zone also presented a significant impact on the SOCD. The order was subfrigid zone (3.63 kg/m²) > cold temperate zone (3.40 kg/m²) > temperate zone (3.39 kg/m²) > warm temperate zone (3.30 kg/m²). The SOCD showed significantly variation along different vegetation zones, with an average value of 2.94 kg/m². The minimum value of 2.15 kg/m² occurred in the low mountain disturbance zone, while the maximum value of 3.6 kg/m² appeared in the alpine meadow zone. The SOCD showed a decreasing trend with the increase of soil thickness, with a reduction range of 14%-70%. On the northern slope of Taibai Mountain, the soil depth was 78 cm in the low mountainous area, whereas it was 33 cm and 10 cm in the middle and high mountainous area, respectively. Total SOCD was 35.45 kg/m², 28.84 kg/m², and 12.29 kg/m² in the low, middle, and high mountainous area, respectively. As opposed, the SOCD at the depth of the unit soil in the low, middle, and high mountainous area was 0.51 kg/m², 0.87 kg/m², and 1.23 kg/m², respectively. The results indicated that, in addition to the elevation gradient, climatic zone, vegetation zone, and soil thickness, the influence of soil depth on soil organic carbon storage cannot be ignored for accurate prediction of soil carbon storage in this area.